In recent years, in order to achieve the safety of members riding in an automobile, a threepoint type seat belt for supporting the breast parts of the members riding in the automobile in a crossed fashion as well as a two-point type seat belt for holding the waist parts have been adopted.
FIG. 43A is a perspective view of the interior of an automobile 1, for explaining the construction of a three-point type seat belt 70. Although the three-point type seat belt may be mounted on all of the front seats and the rear seats of the automobile 1, herein only a driver's seat 2 will be described for simplicity of explanation.
The three-point type seat belt 70 is designed to be put on between the three points of a first anchor 71 provided on the lower part of a center pillar 3, a second anchor 72 mounted on a floor part between a driver's seat 2 and an assistant seat 4 and a third anchor 73 provided on the upper part of the center pillar 3. The three-point type seat belt 70 comprises a waving belt 74 one end of which is attached to the first anchor 71 and the other end of which is folded back at the part of the third anchor 73 and wound by a retractor (not shown) built in the center pillar 3 and a fixed belt 75 one end of which is attached to the second anchor 72 and the other end of which is provided with a buckle 77. A tongue part 76 to be locked in the buckle 77 is provided in an intermediate part of the waving belt 74.
FIG. 43B is a perspective view of a conventional seat belt hanging and holding member 78 to be mounted on the third anchor 73. As illustrated in FIGS. 43B and 43C, the seat belt hanging and holding member 78 comprises a base member 80 made of a steel plate (metal plate) having a bolt-inserting hole 81 and a slot 82 and a coating member 90 made of a synthetic resin for covering the periphery of the slot 82 of the base member 80 and having a seat belt-inserting hole 91 formed in the slot 82. The slot 82 is, as shown in FIG. 43C, punched out, throughout its whole periphery, substantially perpendicularly to the surface of the base member 80. Further, the slot 82 comprises, as illustrated in FIG. 44, long edge parts 82a and 82b opposed to each other, and short edge parts 82c and 82d for connecting together both-the end parts of these long edge parts 82a and 82b. The respective long edge parts 82a and 82b and short edge parts 82c and 82d are, as described above, punched out substantially at right angles with the surface of the base member 80. In addition, the seat belt-inserting hole 91 is, as shown in FIG. 44, formed so as to cover the respective long edge parts 82a and 82b and short edge parts 82c and 82d. A part extending along the one long edge part 82a serves as a folding-back and sliding part 91a for slidingly folding back the waving belt 74.
The seat belt hanging and holding member 78 constructed as mentioned above is fixed to the third anchor 73 by means of a bolt inserted into the bolt-inserting hole 81. Then, the waving belt 74 is slidingly slung and held on the folding-back and sliding part 91a. The waving belt 74 is usually subjected to an aromatic agent process to improve its sliding feature to the coating member 90.
Additionally stated, the seat belt hanging and holding member 78 is, as illustrated in FIG. 43A, formed by molding the coating member 90 integrally with the base member 80 in accordance with, what is called, an insert molding process. In other words, after the base member 80 is inserted into a metal mold for forming the coating member 90, the metal mold is closed and filled with a resin so that the coating member 90 is integrally formed with the base member 80.
In the case of the above described conventional seat belt hanging and holding-member 78, however, since the slot 82 is punched out perpendicularly to the base member 80, the slot 82 is provided with rectangular corner parts. Therefore, rectangular corner parts are formed on the coating member 90 adjacent to the slot 82. There is a risk that stress is concentrated on such rectangular corner parts. That is, there arises a risk that large stress is liable to be concentrated on the part in contact with the slot 82 in the coating member 90. Therefore, in designing the coating member 90, a large safety factor, which is deemed to be more than sufficient, is employed so that a thick coating member 90 is formed so that the coating member 90 is not broken. Accordingly, there has been a problem that the material cost required for the coating member increases, which results in high cost.
Further, in the above mentioned conventional seat belt hanging and holding member 78, as shown in FIG. 44, the waving belt 74 is slidingly slung and held on the folding back and sliding part 91a. When the waving belt 74 is abruptly pulled, however, as shown in FIG. 45, the waving belt 74 sometimes is moved toward the one short edge part 82c side of the slot 82, or as shown in FIG. 46, the waving belt 74 is concentrically gathered together to the short edge 82c side. Particularly, when the waving belt 74 concentrically comes together to the short edge 82c side, a large force is exerted on the coating member 90 from the base member 80, so that the force acting on the coating member 90 needs to be lowered.
Further, in the above mentioned conventional seat belt hanging and holding member 78, there have been problems that the resin tends to leak along the outer peripheral edge parts 83 of the base member 80, as seen in FIG. 47, because of the pressure of the resin in the insert molding and burs 90a are liable to be produced in the boundary parts 83a between the outer peripheral edges 83 and the coating member 90.
Still further, since the base member 80 is generally formed with a carbon steel having, for example, about S55C (SAE1045 to SAE1050), it is subjected to a press molding and then to a thermal treatment so that its strength is improved. Therefore, many production processes are inconveniently needed. Additionally, since deflection is generated on the base member 80 owing to the thermal treatment, when the base member 80 is inserted into the metal mold in order to form the coating member 90 in accordance with the insert molding, an excessive force for correcting the base member to a normal figure is exerted on the metal mold. This undesirably causes the life of the metal mold to be lowered. In addition, when the base member 80 is formed with the material of S55C, there has been a risk that hydrogen brittleness is, during a plating process, generated on the base member 80. Therefore, a thermal treatment to remove the hydrogen brittleness needs to be simultaneously carried out. Consequently, numerous production processes have been disadvantageously required.
Accordingly, a first object of the present invention is to provide a seat belt hanging and holding member capable of reducing manufacturing cost by lowering the material cost required for a coating member while safety is improved.
A second object of the present invention is to provide a seat belt hanging and holding member capable of supporting a force exerted upon the coating member from a base member even if a seat belt is concentrically gathered on, for example, one end side in the longitudinal direction of a slot.
Further, a third object of the present invention is to provide a seat belt hanging and holding member capable of preventing burs formed with the coating member from being produced on the boundary parts between the outer peripheral edge parts of the base member and the coating member.
Still further, a fourth object of the present invention is to provide a seat belt hanging and holding member capable of reducing the number of production processes and improving the duration of life of a metal mold into which the base member is inserted.